The invention relates to a method and apparatus for printing characters so that successive characters are printed closely together in an offset and partially overlapping manner on a record carrier in typewriters or similar office machines.
In typewriters or similar office machines having an erasing, or "self-correcting", system, it is necessary in order to lift off an erroneously printed character by means of a lift-off tape, for the position of the type carrier carriage to be in precise coincidence with the position which it had during printing of that character. A lateral deviation of even 1/100 mm already leaves a residual outline of the character which, although narrow, is clearly visible. For this reason, it is important that the carriage, which is driven, for example, by a motor, be positioned with great precision at all times.
German Patent Application P 29 06 135.6, and counterpart copending U.S. application Ser. No. 121,721, now U.S. Pat. No. 4,311,398, discloses a printing mechanism for realizing an imprint with uniform character spacing wherein after the setting step, the type carrier always performs a pilgrim step-type movement in the same direction with the same step length. This results in identical stopping conditions since any possible play always influences the character position in the same direction. In that proposed printing mechanism, the carriage performs a pilgrim step-type movement if an erroneously printed character is to be removed from the record carrier.
While this printing mechanism makes possible significantly improved corrections compared to other commercially available machines, there still sometimes appears a residual character outline which is visible on the record carrier medium. A further drawback is that this arrangement operates effectively only in one direction and is therefore direction dependent. To emphasize a word or individual words within a brief, the prior art machines produce partially overlapping characters for which special and unidirectionally operating arrangements are used.